LPS-induced Acute Inflammation Research Articles

PSX-A-2 Late-Breaking: Acute Endotoxinemia May Increase Intercostal Temporary Mechanical Nociception in Wethers

Abstract Systemic inflammation induced by lipopolysaccharide (LPS; endotoxin) is associated with generalized hyperalgesia in humans and some animal models. However, the effects of endotoxin-induced inflammation on pain threshold in livestock, such as sheep, is unknown. Eight wethers [~1 year of age; 61.3 ± 0.5 kg BW] were administered saline (2 mL; n = 4) or endotoxin (2 mL; 400 ng of LPS / kg BW; n = 4) intravenously. A handheld algometric unit was used to administer temporary mechanical nociception (TMN) before (Day -2) and after (Day 1) treatment administration by the same person three times at two locations on the right thorax (intercostal spaces 6 and 9). Two-way ANOVA was completed in SAS v9.4 (Cary, NC). There were effects of day (P < 0.001) and location (P < 0.0001) on TMN, such that the force needed to induce TMN on Day -2 (2.04 +/- 0.15 kgF) was less than on Day 1 (2.93 +/- 0.15 kgF) and the force needed to induce TMN at intercostal space 6 (1.81 +/- 0.15 kgF) was less than at intercostal space 9 (3.15 +/- 0.15 kgF). While there was no effect of treatment (P = 0.96), or interaction of treatment and location (P = 0.19), day and location (P = 0.25), or treatment and day and location (P = 0.49), there was a tendency for an interaction of treatment and day (P = 0.06), such that TMN was not different on Day 1 (2.73 +/- 0.30 kgF) and Day -2 (2.24 +/- 0.30 kgF) for animals receiving saline but was greater on Day 1 (3.12 +/- 0.30 kgF) than Day -2 (1.83 +/- 0.30 kgF) for animals receiving LPS. While systemic inflammation is associated with reduced pain threshold in some models, acute LPS-induced inflammation may increase intercostal TMN in castrated sheep.

Terpene-rich fractions of Ficus mucoso (Welw) modulate lipopolysaccharide-induced inflammatory mediators and aberrant permeability of the inner mitochondrial membrane in murine animal model.

Ficus mucoso is traditionally used to treat bronchial infections. This study compared the efficacy of terpene-rich fractions of F. mucoso root bark on lipopolysaccharide(LPS)-induced inflammation, liver mitochondrial permeability transition (mPT), an index of mitochondrial health, and associated pathological alterations. Terpene-Rich Fractions of Dichloromethane (TRDF) and Ethylacetate Fractions of F. mucoso (TREF) were obtained according to standard procedures. To induce systemic inflammation, a single intraperitoneal injection of 1mgLPS/kgbw was given to mice. Spectrophotometric techniques were used to evaluate the effects of the oral administration of TRDF and TREF (3days) on levels of pro-inflammatory mediators (TNF-α, IL-1β, IL-6) using ELSA techniques as well as antioxidant indices in normal and LPS-treated mice. The mPT pore opening, mitochondrial ATPase activity and lipid peroxidation were monitored spectrophotometrically. Our results revealed that treatment with LPS caused significant elevation in serum cytokine levels while administration of 50 and 100mg/kg TRDF and TREF significantly reduced elevated serum levels of cytokines (TNF-α, IL-1β, IL-6) in LPS-challenged mice. In addition, activitities of superoxide dismutase, catalase and liver marker enzymes (ALT and AST) as well as levels of mitochondrial lipid peroxides were significantly reduced in mice treated with TRDF and TREF relative to LPS-fed mice. Furthermore, LPS caused induction of opening of the liver mPT pore which was significantly inhibited by TRDF at 100 and 200mg/kg bw by 71% and 88%, respectively, but only at 100mg/kg TREF. Furthermore, mitochondrial ATPase activity was inhibited largely by TRDF. UPLC-ESI-MS analysis revealed the presence of terpenoid derivatives and a few aromatic metabolites in TRDF. The terpene dominance of TRDF metabolites was further justified on the 1H NMR fingerprint. Overall, TRDF is more effective as a cocktail of anti-inflammatory compounds than TREF against LPS-induced acute systemic inflammation.

Hydroxychloroquine Attenuates Acute Inflammation (LPS)-Induced Apoptosis via Inhibiting TRPV1 Channel/ROS Signaling Pathways in Human Monocytes.

Simple SummaryLPS is a well-known agent in cell line models, including U937 monocytes, for inducing acute inflammation (INF). It is not known whether antioxidant HCQ, through the inhibition of TRPV1 in U937, can decrease oxidative monocyte toxicity and cell death. We investigated the modulator action of HCQ treatment through the modulation of TRPV1 on the levels of mROS, INF, and apoptosis in an LPS-stimulated U937 monocyte model. Acute INF activates apoptotic, inflammatory, and oxidant action through acute INF-dependent excessive cROS, MDA, cytokine generation, and Ca2+ influx in U937 human monocyte cells. Furthermore, treatment with acute INF increases TRPV1 and apoptotic marker (CAS3, CAS9, Bax, and Bcl-2) concentrations via downregulation of glutathione level and glutathione peroxidase activity in U937 monocytes. The acute INF-caused U937 oxidative stress and cytotoxicity is diminished by the treatment of HCQ and TRPV1 inhibitor (CPZ). In summary, treatment with HCQ and CPZ induced anti-inflammatory, anti-apoptotic, and antioxidant action via the inhibition of cROS, cytokine generation, and caspase activation.Acute inflammation (INF) and apoptosis are induced in monocytes by the generation of several factors, including the products of cytosolic oxygen free radicals (cROS) and the excessive influx of Ca2+ via the stimulation of TRPV1. These are main factors in the etiology of monocyte activation-induced inflammatory and neurodegenerative diseases. Importantly, the protective action of hydroxychloroquine (HCQ) treatment via the inhibition of TRPV1 on the levels of inflammatory factors, cROS, and apoptosis in acute INF (lipopolysaccharide, LPS)-exposed neuronal cells was recently reported. However, the relationships between acute INF via TRPV1 activation and HCQ in monocytes have not been fully clarified yet. The cell membrane of U937 human monocytes contains natural TRPV1. In the study plan, we used U937 cells in four main groups, namely control, HCQ (60 μM for 48 h), INF (1 μg/mL LPS for 16 h), and HCQ + INF. The current data indicate that LPS-induced acute INF caused the upregulation of excessive cytosolic Ca2+ accumulation via the stimulation of TRPV1 in the cells. The treatment of INF additionally upregulated the levels of apoptosis and cytokines (IL6, IL1β, and TNFα), due to upregulated cROS and lipid peroxidation levels as well as upregulated generation of caspase -3 (CAS3) and -9 (CAS9) but a decrease in glutathione and glutathione peroxidase. The expression levels of TRPV1, Bax, CAS3, and CAS9 were also upregulated by the treatment of LPS. However, treatment with HCQ and TRPV1 blocker (capsazepine) modulated the levels of cytokines, caspases, cROS, Ca2+ influx, and apoptosis through the modulation of TRPV1 in the U937 that were stimulated with LPS. In summary, the present data suggest TRPV1 activation through the acute INF (LPS)-induced inflammatory, oxidant, and apoptotic adverse actions in monocyte cells, whereas HCQ prevented adverse actions via the modulation of TRPV1. The results may be significant in the modulation of monocyte activation-caused inflammatory and neurodegenerative diseases.

A Peptide Derived from IKK-Interacting Protein Attenuates NF-κB Activation and Inflammation.

The IκB kinase (IKK) complex plays a vital role in regulating the NF-κB activation. Aberrant NF-κB activation is involved in various inflammatory diseases. Thus, targeting IKK activation is an ideal therapeutic strategy to cure and prevent inflammatory diseases related to NF-κB activation. In a previous study, we demonstrated that IKK-interacting protein (IKIP) inhibits the phosphorylation of IKKα/β and the activation of NF-κB through disruption of the formation of IKK complex. In this study, we identified a 15-aa peptide derived from mouse IKIP (46-60 aa of IKIP), which specifically suppressed IKK activation and NF-κB targeted gene expression via disrupting the association of IKKβ and NEMO. Importantly, administration of the peptide reduced LPS-induced acute inflammation and attenuated Zymosan-induced acute arthritis in mice. These findings suggest that this IKIP peptide may be a promising therapeutic reagent in the prevention and treatment of inflammatory diseases.

Abstract MP38: Functional Investigation Of A Novel Adipose Long Intergenic Non-coding RNA, Linc- ADAIN, During Obesity

Background: Long intergenic non-coding RNAs (lincRNAs) are important emerging regulators of cellular functions. Dysfunctional adipose tissue, characterized by increased inflammation and insulin resistance, plays a central role in the development of type 2 diabetes (T2DM) and atherosclerotic cardiovascular diseases. Deep RNA-sequencing of human adipose during low-dose endotoxemia, identified novel lincRNAs shown to be regulated by inflammation and were validated in an independent human cohort, before and after bariatric surgery. LincADAIN was identified as a top candidate that is 1)abundantly expressed in adipose tissue 2)reduced in both obesity-induced chronic and LPS-induced acute inflammation (-77% and -53%, p<0.05). Methods: Knock down(KD) of lincRNAs was carried out via lentiviral expression of shRNA and antisense oligonucleotides (ASOs) in human adipose stromal cells (ASCs)-adipocytes. Subcellular location of LincADAIN was identified through qPCR after cellular fractionation. Biotinylated lincRNA pulldown assay was used to identify interacting proteins by Mass Spectrometry (MS). Results: Human LincADAIN expression negatively correlates to BMI in obese (p<0.001, r2-0.3042) but not lean individuals. PPARγ antagonist treatment showed reduced expression of LincADAIN and PPARγ ChIP-seq peaks indicate that PPARγ may be a transcriptional activator. KD via shRNA of LincADAIN in ASC-adipocytes, increased protein but not mRNA levels of inflammatory cytokines in adipocytes such as IL-8 and MCP-1. Cellular fractionation experiments indicate that LincADAIN is mainly located in the nucleus. MS analysis of biotinylated LincADAIN pulldown proteins revealed many central nuclear and ribosomal proteins as potential interactors, which may be involved in the post-transcriptional mechanism of LincADAIN regulating inflammatory cytokines. Conclusion: These results suggest that LincADAIN is a novel lincRNA with roles in regulating adipose inflammation through nuclear and cytoplasmic actions including modulation of RNA translation. Functional investigations of lincRNAs, such as these are warranted, as recent genomic studies suggest that lincRNAs are likely the causal element driving human disease at some GWAS loci.

Anti-inflammatory effect and mechanism of ethanol extract from Saposhnikoviae Radix in LPS-induced inflammation mouse model

This paper aimed to explore the anti-inflammatory effect of ethanol extract from Saposhnikoviae Radix in a lipopolysaccharide(LPS)-induced inflammation mouse model and its regulation of TLR4/NF-κB signaling pathway. The ethanol extract from Saposhnikoviae Radix was separated and purified on the macroporous adsorption resin and its main chemical components were identified by UPLC-QE/MS. The identification results showed that the top ten components of ethanol extract from Saposhnikoviae Radix were mainly chromones and coumarins. A mouse model of inflammation induced by intraperitoneal injection of LPS was used to investigate the anti-inflammatory effects of ethanol extract from Saposhnikoviae Radix after intragastric administration for seven successive days. Mice in all groups except for the control group were treated with intraperitoneal injection of LPS(0.015 g·kg~(-1)) one hour after the last administration, and twelve hours later, the blood was sampled and separated and the broncoalveolar lavage fluid(BALF) was collected. The levels of nitric oxide(NO), tumor necrosis factor-α(TNF-α), interleukin-6(IL-6), and interleukin-1β(IL-1β) in mouse serum and BALF were detected by ELISA. The harvested lung tissue was stained with hematoxylin-eosin(HE) for observing the pathological changes, followed by the detection of protein expression levels of related molecules in TLR4/NF-κB signaling pathway by Western blotting. The results showed that the ethanol extract from Saposhnikoviae Radix significantly ameliorated the pathological conditions in lung tissue of model mice, reversed the increase in NO, TNF-α, IL-6, and IL-1β levels of mouse serum and BALF, down-regulated the protein expression levels of Toll-like receptor 4(TLR4), myeloid differentiation factor(MyD88), and phosphorylated nuclear transcription factor κB-p65/nuclear transcription factor κB-p65(P-NF-κB p65/NF-κB p65), and up-regulated the NF-κB inhibitory protein α(IκBα). The ethanol extract from Saposhnikoviae Radix exhibited a good anti-inflammatory effect in the LPS-induced acute inflammation muse model, which might be related to the inhibition of the activation of TLR4/NF-κB inflammatory signaling pathway. Chromones and coumarins have been proved to be the active components for its anti-inflammatory effects.

The Role of HSP70 in the Protective Effects of NVP-AUY922 on Multiple Organ Dysfunction Syndrome in Endotoxemic Rats.

Sepsis is defined as a life-threatening organ dysfunction syndrome with high morbidity and mortality caused by bacterial infection. The major characteristics of sepsis are systemic inflammatory responses accompanied with elevated oxidative stress, leading to multiple organ dysfunction syndrome (MODS), and disseminated intravascular coagulation (DIC). As a molecular chaperon to repair unfolded proteins, heat shock protein 70 (HSP70) maintains cellular homeostasis and shows protective effects on inflammatory damage. HSP 90 inhibitors were reported to exert anti-inflammatory effects via activation of the heat shock factor-1 (HSF-1), leading to induction of HSP70. We evaluated the beneficial effect of HSP 90 inhibitor NVP-AUY 922 (NVP) on multiple organ dysfunction syndrome induced by lipopolysaccharide (LPS) and further explored the underlying mechanism. NVP (5 mg/kg, i.p.) was administered 20 h prior to LPS initiation (LPS 30 mg/kg, i.v. infusion for 4 h) in male Wistar rats. Results demonstrated that pretreatment with NVP significantly increased survival rate and prevented hypotension at 6 h after LPS injection. Plasma levels of ALT, CRE and LDH as well as IL-1β and TNF-α were significantly reduced by NVP at 6 h after LPS challenge. The induction of inducible NO synthase in the liver, lung and heart and NF-κB p-p65 and caspase 3 protein expression in the heart were also attenuated by NVP. In addition, NVP markedly induced HSP70 and HO-1 proteins in the liver, lung and heart after LPS injection. These results indicated that NVP possessed the anti-inflammatory and antioxidant effects on LPS-induced acute inflammation, which might be associated with HSP70 and HO-1, leading to prevent MODS in sepsis. NVP might be considered as a novel therapeutic strategy in the prevention of sepsis-induced MODS.

C646 Protects Against DSS-Induced Colitis Model by Targeting NLRP3 Inflammasome.

Numerous pieces of evidence have identified that the NLRP3 inflammasome plays a pivotal role in the development and pathogenesis of colitis. Targeting the NLRP3 inflammasome represents a potential therapeutic treatment. Our previous studies have suggested that acetylation of NLRP3 is indispensable to NLRP3 inflammasome activation, and some acetyltransferase inhibitors could suppress the NLRP3 inflammasome activation. Here, we identified that C646, an inhibitor of histone acetyltransferase p300, exerts anti-inflammatory effects in DSS-induced colitis mice by targeting the NLRP3 inflammasome. Mechanistically, C646 not only inhibits NF-κB activation, leading to the decreased expression of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) and NLRP3, but also suppresses the NLRP3 inflammasome assembly by disrupting the interaction between NLRP3 and ASC. In addition, C646 attenuated the LPS-induced acute systemic inflammation model. Thus, our results demonstrate the ability of C646 to suppress the NLRP3 inflammasome activity and its potential application in the treatment of inflammatory bowel disease.

Effect of lipopolysaccharide on peripheral tissue and hypothalamic expression of metabolic and inflammatory markers in mice fed high-fat diets with distinct 18-carbon fatty acid composition.

Physiological and metabolic effects of fatty acids are determined by their degree of saturation and chain length. Effects of 18-carbon fatty acids with various degrees of saturation on inflammatory, oxidative, and neuropeptide gene transcription, especially in the hypothalamus, in response to LPS-induced acute inflammation have not been well studied. We conducted this study to test whether diets with distinct 18-carbon fatty acid differentially affect inflammatory and metabolic response to LPS exposure in the hypothalamus, liver, and muscle tissues. Four experimental diets were fed for 4 weeks to male C57BL/6J mice, and a terminal 4-h lipopolysaccharide (LPS) injection was administered. Diets included a control diet (CON) containing 5.6% kcal fat from lard and 4.4% kcal fat from soybean oil, and three high-fat diets (HFD) containing 25% kcal fat from lard and 20% kcal fat from either shea butter (SHB; saturated fatty acid-rich fat), olive oil (OLO; monounsaturated fatty acid-rich oil), or soybean oil (SBO; polyunsaturated fatty acid-rich fat). Compared to CON, HFD-fed mice had higher weight gain and body fat accumulation. The SBO group had lowest Cpt1b expression in the liver, and OLO group had the lowest Pomc and the highest Lepr expression in the hypothalamus. LPS challenge increased pro-inflammatory cytokine mRNA expression in the brain and peripheral tissues. However, the diets did not exert distinguishable effects on LPS-induced inflammatory responses. Therefore, saturation degree of 18-carbon fatty acids may not play a critical role in their effects on inflammatory and metabolic indicators in response to acute inflammation induced by LPS.

Iron-dependent apoptosis causes embryotoxicity in inflamed and obese pregnancy

Iron is essential for a healthy pregnancy, and iron supplementation is nearly universally recommended, regardless of maternal iron status. A signal of potential harm is the U-shaped association between maternal ferritin, a marker of iron stores, and risk of adverse pregnancy outcomes. However, ferritin is also induced by inflammation and may overestimate iron stores during inflammation or infection. In this study, we use mouse models to determine whether maternal iron loading, inflammation, or their interaction cause poor pregnancy outcomes. Only maternal exposure to both iron excess and inflammation, but not either condition alone, causes embryo malformations and demise. Maternal iron excess potentiates embryo injury during both LPS-induced acute inflammation and obesity-induced chronic mild inflammation. The adverse interaction depends on TNFα signaling, causes apoptosis of placental and embryo endothelium, and is prevented by anti-TNFα or antioxidant treatment. Our findings raise important questions about the safety of indiscriminate iron supplementation during pregnancy.

JAK2V617F Hematopoietic Stem Cells Exhibit a Blunted Response to Acute Inflammation

Increased inflammation is common in patients with myeloproliferative neoplasms (MPN) and drives many of the debilitating constitution symptoms associated with the disease.Inflammation drives hematopoietic stem cells (HSC) out of quiescence and into cycle. Takizawa et al. (Cell Stem Cell, 2017) recently showed that Toll-like receptor 4 (TLR4) activation induces proliferative stress in HSCs that is mediated by reactive oxygen species (ROS). This proliferation stress impairs HSC regenerative ability and competitive fitness. We propose that chronic inflammation has a central role in the clonal expansion of JAK2V617F HSCs for several reasons. First, JAK2V617F monocytes from MPN patients produce elevated amounts of the inflammatory cytokine tumor necrosis factor-alpha (TNF) for a prolonged period of time following stimulation with lipopolysaccharide (LPS), a major component of Gram-negative bacteria. Secondly, there is a positive correlation between TNF concentration in plasma and JAK2V617F allele burden suggesting that TNF promotes expansion of the JAK2V617F clone. Finally, JAK2V617F mutant cells fail to expand in TNF-/- mice. Thus, we hypothesize that the JAK2V617F mutation protects hematopoietic stem cells from inflammation giving them a selective advantage in the context of chronic inflammation.To investigate the response of JAK2V617F HSCs to acute inflammation, we injected mice with a single dose of 35 μg LPS then quantified HSCs (defined as Lineage-ckit+Sca-1+CD150+CD48-) after 24 hours. Vehicle-treated controls were injected with sterile PBS. Following acute inflammation, the frequency of wild-type HSCs significantly expanded compared to vehicle-treated controls (p = 0.027). The frequency of JAK2V617F HSCs did not significantly expand following acute inflammation. To model chronic inflammation, we injected mice daily with 5 μg LPS for 4-6 weeks. The frequency of either wild-type or JAK2V617F HSCs did not significantly change following 4-6 weeks of chronic TLR4 stimulation.LPS is commonly used to induce inflammation by activating signaling pathways downstream of the Toll-like receptor 4 (TLR4), including MyD88 and TRIF-p38MAPK. TLR4 activation also increases reactive oxygen species (ROS), leading to cell proliferation and DNA damage. To detect intracellular ROS, we treated HSCs with a ROS/RNS sensitive dye (CM-H2DCFDA) then analyzed HSCs by flow cytometry. Following acute LPS stimulation, wild-type HSCs had significantly elevated ROS compared to vehicle-treated controls (p = 0.001). JAK2V617F HSCs did not exhibit a significant increase in ROS following acute LPS treatment. Finally, we analyzed LPS-induced DNA damage in JAK2V617F and wild-type HSCs by quantifying γH2AX foci using the Amnis Imagestream flow cytometer. The percent of wild-type HSCs with greater than three γH2AX+ foci was significantly increased following LPS treatment. However, the percent of JAK2V617F HSCs with greater than three γH2AX+ foci was not significantly increased following LPS stimulation.In conclusion, JAK2V617F HSCs exhibit reduced proliferation, ROS and DNA damage compared to normal HSCs in response to acute LPS-induced inflammation. Because inflammation-induced HSC exhaustion is mediated by induction of the TLR4-TRIF-ROS axis, JAK2V617F HSCs may be protected from ROS-induced proliferative stress, allowing for their selection in the context of chronic inflammation. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Protective Effects of Microbiome-Derived Inosine on Lipopolysaccharide-Induced Acute Liver Damage and Inflammation in Mice via Mediating the TLR4/NF-κB Pathway.

This research assessed the anti-inflammatory and hepatoprotective properties of inosine and the associated mechanism. Inosine pretreatment significantly reduced the secretion of several inflammatory factors and serum alanine transaminase (ALT) and aspartate amino transferase (AST) levels in a dose-dependent manner compared with the lipopolysaccharide (LPS) group. In LPS-treated mice, inosine pretreatment significantly reduced the ALT and malondialdehyde (MDA) concentration and significantly elevated the antioxidant enzyme activity. Furthermore, inosine pretreatment significantly altered the relative abundance of the genera, Bifidobacterium, Lachnospiraceae UCG-006, and Muribaculum. Correlation analysis showed that Bifidobacterium and Lachnospiraceae UCG-006 were positively related to the cecal short-chain fatty acids but negatively related to the serum IL-6 and hepatic AST and ALT levels. Notably, inosine pretreatment significantly modulated the hepatic TLR4, MYD88, NF-κB, iNOS, COX2, AMPK, Nfr2, and IκB-α expression. These results suggested that inosine pretreatment alters the intestinal microbiota structure and improves LPS-induced acute liver damage and inflammation through modulating the TLR4/NF-κB signaling pathway.

The role of circTMOD3 in regulating LPS-induced acute inflammation and injury in human lung fibroblast WI-38 cells

Background Circular RNAs (circRNAs) have been implicated in the molecular etiology of pediatric pneumonia. Here, we investigated the precise action of circRNA tropomodulin 3 (circTMOD3, hsa_circ_0035292) in cell injury and inflammation induced by lipopolysaccharide (LPS). Methods: Cell viability was gauged by Cell Counting Kit-8 (CCK-8) assay. Cell apoptosis and cycle distribution were assessed by flow cytometry. Enzyme-linked immunosorbent assay (ELISA) was used to measure interleukin-6 (IL-6), IL-1β and tumor necrosis factor alpha (TNF-α) production. The levels of circTMOD3, microRNA (miR)-146b-3p, and C–X–C motif chemokine receptor 1 (CXCR1) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot. Ribonuclease (RNase) R, Actinomycin D and subcellular localization assays were done to characterize circTMOD3. The direct relationship between miR-146b-3p and circTMOD3 or CXCR1 was confirmed by dual-luciferase reporter assays. Results: Our data showed that LPS induced the expression of circTMOD3 in WI-38 cells. CircTMOD3 was resistant to RNase R and was mainly present in the cytoplasm. Silencing endogenous circTMOD3 alleviated WI-38 cell injury and inflammation triggered by LPS. Mechanistically, circTMOD3 directly targeted miR-146b-3p, and CXCR1 was a direct and functional target of miR-146b-3p. CircTMOD3 regulated LPS-induced cell inflammation and injury by targeting miR-146b-3p, and miR-146b-3p-mediated suppression of CXCR1 impacted LPS-evoked cytotoxicity and inflammation. Furthermore, circTMOD3 functioned as a competing endogenous RNA (ceRNA) for miR-146b-3p to induce CXCR1 expression. Conclusion: Our findings demonstrated the regulation of circTMOD3 in LPS-induced cell injury and inflammation at least partially via miR-146b-3p-independent modulation of CXCR1.

Inflammation-Induced Histamine Impairs the Capacity of Escitalopram to Increase Hippocampal Extracellular Serotonin.

Commonly prescribed selective serotonin reuptake inhibitors (SSRIs) inhibit the serotonin transporter to correct a presumed deficit in extracellular serotonin signaling during depression. These agents bring clinical relief to many who take them; however, a significant and growing number of individuals are resistant to SSRIs. There is emerging evidence that inflammation plays a significant role in the clinical variability of SSRIs, though how SSRIs and inflammation intersect with synaptic serotonin modulation remains unknown. In this work, we use fast in vivo serotonin measurement tools to investigate the nexus between serotonin, inflammation, and SSRIs. Upon acute systemic lipopolysaccharide (LPS) administration in male and female mice, we find robust decreases in extracellular serotonin in the mouse hippocampus. We show that these decreased serotonin levels are supported by increased histamine activity (because of inflammation), acting on inhibitory histamine H3 heteroreceptors on serotonin terminals. Importantly, under LPS-induced histamine increase, the ability of escitalopram to augment extracellular serotonin is impaired because of an off-target action of escitalopram to inhibit histamine reuptake. Finally, we show that a functional decrease in histamine synthesis boosts the ability of escitalopram to increase extracellular serotonin levels following LPS. This work reveals a profound effect of inflammation on brain chemistry, specifically the rapidity of inflammation-induced decreased extracellular serotonin, and points the spotlight at a potentially critical player in the pathology of depression, histamine. The serotonin/histamine homeostasis thus, may be a crucial new avenue in improving serotonin-based treatments for depression.SIGNIFICANCE STATEMENT Acute LPS-induced inflammation (1) increases CNS histamine, (2) decreases CNS serotonin (via inhibitory histamine receptors), and (3) prevents a selective serotonin reuptake inhibitor (SSRI) from effectively increasing extracellular serotonin. A targeted depletion of histamine recovers SSRI-induced increases in extracellular hippocampal serotonin.

Reduced expression of MiR-125a-5p aggravates LPS-induced experimental acute kidney injury pathology by targeting TRAF6

AimsPatients with acute kidney injury (AKI) have higher mortality, and sepsis is among its main causes. MicroRNAs (miRNAs) are essential for regulating kidney function and could have curative potential. This study explored the possibility to treat AKI with miR-125a-5p and reveal the possible mechanism. Materials and methodsLPS-induced mouse model and LPS-induced RAW264.7 cell model of AKI were established and treated with miR-125a-5p mimics or inhibitors. Serum creatinine and blood urea were measured to evaluate kidney function. The pathological changes of kidney tissues were detected by H&E and PAS staining technique, and the infiltration of macrophages were observed by immunohistochemistry. RAW264.7 cell viability, TRAF6 and cytokines expressions under LPS stimulation were measured. The role and therapeutic potential of miR-125a-5p were verified in vivo and in vitro after given miR-125a-5p mimics or inhibitors. Key findingsLPS-induced mice had increasing serum creatinine and urea, and evident pathological changes, including severe tubular dilatation and macrophages infiltration. TRAF6 expression in the kidney was significantly higher, while miR-125a-5p expression was suppressed. MiR-125a-5p targeted TRAF6, and its overexpression deactivated NF-κB signaling pathway, reducing downstream TNF-α, IL-1β and IL-6 expressions. MiR-125a-5p mimics rescued LPS-induced kidney damage and suppressed pro-inflammatory cytokines expression through inhibiting TRAF6/NF-κB axis. SignificanceWe highlighted that miR-125a-5p could inhibit LPS-induced acute inflammation in the kidney through targeting TRAF6/NF-κB axis. These results might contribute to the development of molecular therapy in AKI.

α/β‐Hydrolase Domain‐6 Regulates Macrophage Polarization and its Inhibition Protects Against LPS‐Induced Inflammation

The activated M1 macrophages exhibit pro-inflammatory activity and contribute to diverse inflammatory disorders, such as microbial infection, sepsis, autoimmune diseases, and cardiometabolic disorders. Thus, targeting macrophage polarization towards an anti-inflammatory M2 phenotype may provide a strategy to treat inflammatory diseases. Deletion of the monoacylglycerol lipase α/β-hydrolase domain-6 (ABHD6) demonstrated the therapeutic potential of targeting ABHD6 against obesity, type-2-diabetes, and other inflammatory disorders. However, the role of ABHD6 in macrophage activation/polarization under inflammatory conditions remains to be ascertained. Using macrophage cell lines, a pharmacological approach, and whole-body ABHD6 KO mice, we investigated whether ABHD6 suppression is protective against lipopolysaccharide (LPS)-induced inflammation. Pharmacological inhibition of ABHD6 activity with a potent inhibitor (KT203) in RAW264.7 and J774A.1 macrophages attenuates LPS-induced expression of pro-inflammatory cytokines (Tnfa and Mcp1). In addition, ABHD6 inhibition results in decreased LPS-induced secretion of TNFα and MCP1 from RAW264.7 macrophages. Interestingly, absence of ABHD6 activity promotes LPS-primed macrophage polarization towards the M2 phenotype, as evidenced by the increased arginase-1 (Arg1) expression. Furthermore, whole-body ABHD6 KO mice, compared to the wild-type controls, show lower susceptibility to systemic LPS-induced inflammation as indicated by a decline in plasma TNFα and MCP-1 levels and reduced expression of pro-inflammatory markers (Cd68 and Il1b) in peripheral blood mononuclear cells and lung tissue. Finally, ABHD6 KO mediated protection against acute LPS-induced inflammation is more prominent in female versus male mice. Taken together, our data support a pro-inflammatory role for ABHD6 under LPS-induced condition. ABHD6 inhibition switches LPS-induced macrophage polarization towards an anti-inflammatory M2 state, and ABHD6 deletion in mice attenuates systemic response to LPS challenge. The results suggest the therapeutic potential of ABHD6 inhibition for the treatment of inflammation-associated disorders.

The hypoferremic response to acute inflammation is maintained in thalassemia mice even under parenteral iron loading

BackgroundHepcidin controls iron homeostasis by inducing the degradation of the iron efflux protein, ferroportin (FPN1), and subsequently reducing serum iron levels. Hepcidin expression is influenced by multiple factors, including iron stores, ineffective erythropoiesis, and inflammation. However, the interactions between these factors under thalassemic condition remain unclear. This study aimed to determine the hypoferremic and transcriptional responses of iron homeostasis to acute inflammatory induction by lipopolysaccharide (LPS) in thalassemic (Hbbth3/+) mice with/without parenteral iron loading with iron dextran.MethodsWild type and Hbbth3/+ mice were intramuscularly injected with 5 mg of iron dextran once daily for two consecutive days. After a 2-week equilibration, acute inflammation was induced by an intraperitoneal injection of a single dose of 1 µg/g body weight of LPS. Control groups for both iron loading and acute inflammation received equal volume(s) of saline solution. Blood and tissue samples were collected at 6 hours after LPS (or saline) injection. Iron parameters and mRNA expression of hepcidin as well as genes involved in iron transport and metabolism in wild type and Hbbth3/+ mice were analyzed and compared by Kruskal–Wallis test with pairwise Mann–Whitney U test.ResultsWe found the inductive effects of LPS on liver IL-6 mRNA expression to be more pronounced under parenteral iron loading. Upon LPS administration, splenic erythroferrone (ERFE) mRNA levels were reduced only in iron-treated mice, whereas, liver bone morphogenetic protein 6 (BMP6) mRNA levels were decreased under both control and parenteral iron loading conditions. Despite the altered expression of the aforementioned hepcidin regulators, the stimulatory effect of LPS on hepcidin mRNA expression was blunt in iron-treated Hbbth3/+ mice. Contrary to the blunted hepcidin response, LPS treatment suppressed FPN1 mRNA expression in the liver, spleen, and duodenum, as well as reduced serum iron levels of Hbbth3/+ mice with parenteral iron loading.ConclusionOur study suggests that a hypoferremic response to LPS-induced acute inflammation is maintained in thalassemic mice with parenteral iron loading in a hepcidin-independent manner.

ABCA7 Regulates Brain Fatty Acid Metabolism During LPS-Induced Acute Inflammation.

The ATP binding cassette subfamily A member 7 (ABCA7) gene is one of the significant susceptibility loci for Alzheimer’s disease (AD). Furthermore, ABCA7 loss of function variants resulting from premature termination codon in the gene are associated with increased risk for AD. ABCA7 belongs to the ABC transporter family, which mediates the transport of diverse metabolites across the cell membrane. ABCA7 is also involved in modulating immune responses. Because the immune system and lipid metabolism causatively engage in the pathogenesis of AD, we investigated how ABCA7 haplodeficiency modulates the metabolic profile in mouse brains during acute immune response using a metabolomics approach through LC/Q-TOF-MS. Peripheral lipopolysaccharide (LPS) stimulation substantially influenced the metabolite content in the cortex, however, the effect on metabolic profiles in Abca7 heterozygous knockout mice (Abca7±) was modest compared to that in the control wild-type mice. Weighted gene co-expression network analysis (WGCNA) of the metabolomics dataset identified two modules influenced by LPS administration and ABCA7 haplodeficiency, in which glycerophospholipid metabolism, linoleic acid metabolism, and α-linolenic acid metabolism were identified as major pathways. Consistent with these findings, we also found that LPS stimulation increased the brain levels of eicosapentaenoic acid, oleic acid, and palmitic acid in Abca7± mice, but not control mice. Together, our results indicate that ABCA7 is involved in the crosstalk between fatty acid metabolism and inflammation in the brain, and disturbances in these pathways may contribute to the risk for AD.

Columbianadin Dampens In Vitro Inflammatory Actions and Inhibits Liver Injury via Inhibition of NF-κB/MAPKs: Impacts on ∙OH Radicals and HO-1 Expression.

Columbianadin (CBN), a natural coumarin isolated from Angelica decursiva, is reported to have numerous biological activities, including anticancer and platelet aggregation inhibiting properties. Here, we investigated CBN’s anti-inflammatory effect in lipopolysaccharide (LPS)-stimulated RAW 264.7 cell activation and deciphered the signaling process, which could be targeted by CBN as part of the mechanisms. Using a mouse model of LPS-induced acute liver inflammation, the CBN effects were examined by distinct histologic methods using trichrome, reticulin, and Weigert’s resorcin fuchsin staining. The result showed that CBN decreased LPS-induced expressions of TNF-α, IL-1β, and iNOS and NO production in RAW 264.7 cells and mouse liver. CBN inhibited LPS-induced ERK and JNK phosphorylation, increased IκBα levels, and inhibited NF-κB p65 phosphorylation and its nuclear translocation. Application of inhibitors for ERK (PD98059) and JNK (SP600125) abolished the LPS-induced effect on NF-κB p65 phosphorylation, which indicated that ERK and JNK signaling pathways were involved in CBN-mediated inhibition of NF-κB activation. Treatment with CBN decreased hydroxyl radical (•OH) generation and increased HO-1 expression in RAW 264.7 cells. Furthermore, LPS-induced liver injury, as indicated by elevated serum levels of liver marker enzymes (aspartate aminotransferase (AST) and alanine aminotransferase (ALT)) and histopathological alterations, were reversed by CBN. This work demonstrates the utility of CBN against LPS-induced inflammation, liver injury, and oxidative stress by targeting JNK/ERK and NF-κB signaling pathways.

Photoperiod alters the choroid plexus response to LPS-induced acute inflammation in EWES

Abstract This study determined the influence of photoperiod on the expression of toll-like receptor 2 and 4 (TLR2 and TLR4), interleukin 1□ (IL1B), IL-1 receptor type I (IL1R1) and II (IL1R2), interleukin 6 (IL6), the IL-6 receptor (IL6R) and signal transducer (IL6ST), tumor necrosis factor α (TNF), and TNF□ receptor type I (TNFRSF1A) and II (TNFRSF1B) in the choroid plexus (ChP) of ewes with lipopolysaccharide (LPS)-induced acute inflammation. Under short-days (SD, n = 12, anestrous) and long-days (LD, n = 12, synchronized follicular phase), ewes were treated with saline or LPS. Compared to LD conditions, the ewes under SD were characterized by a greater (P<0.05) area under the curve (AUC) of cortisol in the LPS-treated group and by a lower (P<0.05) AUC of prolactin in the saline-treated group. Under both photoperiods, LPS increased (P<0.05) the expression of all examined genes except for TNFRSF1B (only under SD), TNF and TNFRSF1A (no stimulation), and IL6R (decreased (P<0.05) under SD). The LPS-induced increases in TLR2, TLR4, IL1B and its receptors, IL6 and TNFRSF1B were higher (P<0.05) under SD than LD. TLR4 was positively correlated with IL1B and IL6 in both saline- (r2 = 0.64, P<0.01 and r2 = 0.52, P<0.01) and LPS-treated (r2 = 0.81, P<0.0001 and r2 = 0.51, P<0.001) ewes. IL1B (r2 = 0.56, P<0.01 and r2 = 0.77, P<0.0001) and IL6 (r2 = 0.77, P<0.005 and r2 = 0.35, P<0.05) were positively correlated with TLR2 in saline- and LPS-treated ewes, respectively. This indicates that in ewes, the ChP response to acute systemic inflammation is dependent upon the photoperiod with stronger effects being observed under SD. Our results also suggest that gonadal hormones altering TLR4 signaling events are involved in the photoperiodic modulation of the ChP response to LPS. Further experiments are required to explain the mechanism involved in this phenomenon.